class_docstr: Registry responsible for built-in keras layers.
code: def _is_rnn_layer(cls, layer):
      return layer.__class__ in cls._RNN_LAYERS
  
file_path: model-optimization/tensorflow_model_optimization/python/core/sparsity/keras/prune_registry.py
imports: import tensorflow
  from tensorflow_model_optimization.python.core.sparsity.keras import prunable_layer
label_desc: Use image node_id 3 for calling the PruneRegistry obj's underlying member method code with example usage: obj._is_rnn_layer(cls, layer) and returns: unknown